- #36

- 22,471

- 13,395

No, the charge of the electron is defined to be ##-e## in the SI. As detailed in #27 the ingredient of ##\alpha## that's not defined since 2019 by defining the units s, m, kg, and A, is the "permittivity of the vacuum", ##\epsilon_0## which is now to be measured. The same holds for the "permeability of the vacuum", ##\mu_0##, which now is no longer defined but has to be measured. In the SI before 2019 (since 1948 or so) ##\mu_0## was defined through the definition of the A via the force of two infinitelylong straight wires of negligible width: ##\mu_0^{(\text{old})}=4 \pi \cdot 10^{-7} \text{N} \cdot \text{A}^{-2}##. Now it's to be measured and the current value is ##μ_0^{(\text{new})} = 1.25663706212(19) \cdot 10^{-6} \text{N}\cdot \text{A}^{-2}##.α is absolutely not the speed of light morphed into a dimensionless form.

Insofar as it is anything at all besides α, it is the charge of the electron morphed into a dimensionless form.

c is a factor that comes about because we historically measured time in seconds and length in meters. (And is equal to a dimensionless 1 in sane units). It's a conversion factor, like the dozen. No more, no less. It tells us about spacetime, not electromagnetism.